Description:
A very high boiling impurity was concentrated from a sample of FEFO with a hexane wash. Additional washing of this sample has increased the concentration of this impurity. A mass spectrum was obtained but an identification has not been made. The results of the analysis of the products from the thermal decomposition of FEFO at 120, 135, 150 C are discussed. A chromatogram of FEFO heated for 22 hours at 150 C shows a definite increase in low and high boiling impurities. The evaluation of the condition of the two coupon test assemblies aged at 80 C for 21 and 27 months are discussed. Thermal analysis of the LX-09 from these two coupon tests, a PASS A mechanical test specimen and a control sample are reported. A PDP-12/30 was interfaced with a Perkin Elmer DSC-1 to measure the heat of fusion of PETN. Some of the problems associated with getting reproducible data are discussed. The heat of fusion for six lots of LX-13 grade PETN are given.

Description:
Changes in the loading technique for the Henkin test to be used when investigating high temperatures explosives are reported. Data comparing times-to-explosion for lead, aluminum {open_quotes}foil{close_quotes}, insulated lead, and insulated aluminum {open_quotes}foil{close_quotes} plugs are included. A preliminary temperature-time curve for an HMX sample in the Henkin batch at 272{degrees}C, is reported. The pyrolysis apparatus has been reworked to increase its sensitivity and the results of the changes are readily apparent in the pyrolytic decomposition curves that are reported. Thermal data are reported for some {open_quotes}tailormade{close_quotes} samples of HMX, samples of PETN from different manufacturers, and the six simulated samples of Bridgewater HMX. Differences within these groups are detected by one or another of the tests. Work has begun on a two column gas chromatograph to be used in obtaining chemical reactivity data for use in specifications.

Description:
Infrared and UV spectra have been obtained on oils pressed from GE5601 silicone rubber. A method for depositing oil on PETN has also been investigated. In order to determine if the oil was evenly deposited on the PETN, an analytical method was developed for determining the concentration of oil on PETN.

Description:
The thermally aged LX-09 skid test parts were disassembled; the Dow Corning 93-120 silicone used to pot the parts in the aluminum hemisphere was reverting. Thermal analysis of LX-09 samples taken at various locations in the past do not show any variations. Analyses of the atmosphere from six PASS LX-09 mechanical test specimens are reported. The technique used to isolate two of the low boiling impurities in FEFO are discussed and an IR spectrum of one is reported. The results from the thermal analysis of XTX (sample WSI-730) are discussed. A system for taking digital data from a DSC-1 and the technique used to analyze these data are discussed. Some preliminary runs made on PETN and indium are reported.

Description:
We demonstrate that the introduction of microvoids as glass microballoons sensitizes high-density solvent-pressed PETN to shock initiation. At input pressures ranging from 1.4-2.0 GPa, shock propagation velocities are higher and run distances to detonation are shorter for PETN sensitized by microballoons. By selecting the size and density of microballoons, we can therefore study the effect of void size and density on shock initiation by hot spots.

Description:
Henkin`s test data are reported for comparisons of the following: dry-to-moist samples, PBX 9404 in brass and gold-plated blasting caps, Holston HMX with Bridgewater HMX, LX-04-1 and LX-04-1 + Ucon oil, and PETN, LX-04-1 and Extex. The time-to-explosion curves for HMX and PBX 9404 are also given. A description of the pyrolysis apparatus and the method of calibrating the sample temperature to the response of the thermal conductivity detector are reported. The pyrolytic decomposition curves of several standard explosives and six specially prepared HMX samples (LRL raw material No. A-311 through A-316) are included. A controlled atmosphere D.T.A. is described and the thermograms of PETN with an atmosphere of air at 85 psi, nitrogen at 85 psi and 200 psi are given. The thermograms indicate that PETN becomes more sensitive as the pressure increases. Chemical reactivity data are reported for Comp B, Comp B-3, Comp C-4, HMX, PBX 9011, PBX 9205, Tetryl and TNT. Also, test results are reported for LX-01-1 and Comp B-3 heated at 150{degrees}C for 22 hours, LX-02-1 heated at 100{degrees}C for 22 hours, and pressed pellets of PBX 9404 and PBX 9404 + powdered lead.

Description:
Pentaerythritol tetranitrate (PETN) is used throughout the stockpile as an energetic material. The formulation of PETN into XTX8003 (80% PETN, 20% Sylgard 182) creates an extrudable energetic composite. PETN and XTX8003 are used in the firesets for the retired W68 (MC2370) and the W76 (MC3028). When faced with potential lifetime extensions, energetic materials are naturally suspect regarding their output after prolonged aging. The authors have studied PETN and XTX8003 by looking at 25-year-old samples from retired MC2370s and newer materials. Both the old and new materials have also been placed in various accelerated aging protocols to investigate any decomposition that might occur over time. PETN is known to decompose autocatalytically even in the early stages of decomposition, but the process is poorly understood. Published values for the activation energy of decomposition vary by >40 kcal/mol. The 12 million year half life predicted for room temperature PETN would be dramatically shortened by chemical influences that lead to lower energy decomposition pathways. Degree of confinement, purity, and crystal size all influence degradation rates. In this paper, the authors observe the effects of chemical and thermal aging on PETN. They anticipate changes in mechanism at higher temperature aging, and before trying to extrapolate to lower temperatures, they want to make sure that they understand the different chemical processed involved.

Description:
Some orientations of PETN crystals have anomalously high shock initiation sensitivity around 4 to 5 GPa. Results of a series of laser interferometry experiments at 4.2 GPa show that this is associated with an elastic-plastic, two-wave structure with large elastic precursors. Implications for the initiation mechanism in single crystals is discussed. Initial work on beta phase, monoclinic HMX is also described.

Description:
The 110{degrees}C thermal aging parameters, including initial rates of decomposition, of four types of pentaerythritol tetranitrate (PETN) over a period of ten months are presented. Both decomposition products nitric oxide, NO, and nitrogen dioxide, N0{sub 2} were monitored from multiple, hermetically-sealed, in vacuo samples. Nitric oxide appears to be the first nitrogen oxide product evolved. Nitrogen dioxide produced by abrupt thermal aging is more slowly converted to nitric oxide by a 1:1 process. The behavior of samples of RR5K PETN was significantly different from that of other powders studied. Further work is in progress to better define the thermal aging of RR5K PETN.

Description:
Currently, the critical particle properties of pentaerythritol tetranitrate (PETN) that influence deflagration-to-detonation time in exploding bridge wire detonators (EBW) are not known in sufficient detail to allow development of a predictive failure model. The specific surface area (SSA) of many PETN powders has been measured using both permeametry and gas absorption methods and has been found to have a critical effect on EBW detonator performance. The permeametry measure of SSA is a function of particle shape, packed bed pore geometry, and particle size distribution (PSD). Yet there is a general lack of agreement in PSD measurements between laboratories, raising concerns regarding collaboration and complicating efforts to understand changes in EBW performance related to powder properties. Benchmarking of data between laboratories that routinely perform detailed PSD characterization of powder samples and the determination of the most appropriate method to measure each PETN powder are necessary to discern correlations between performance and powder properties and to collaborate with partnering laboratories. To this end, a comparison was made of the PSD measured by three laboratories using their own standard procedures for light scattering instruments. Three PETN powder samples with different surface areas and particle morphologies were characterized. Differences in bulk PSD data generated by each laboratory were found to result from variations in sonication of the samples during preparation. The effect of this sonication was found to depend on particle morphology of the PETN samples, being deleterious to some PETN samples and advantageous for others in moderation. Discrepancies in the submicron-sized particle characterization data were related to an instrument-specific artifact particular to one laboratory. The type of carrier fluid used by each laboratory to suspend the PETN particles for the light scattering measurement had no consistent effect on the resulting PSD data. Finally, the SSA of the three powders was measured using both ...

Description:
Using the energetic material Pentaerythritol Tetranitrate (PETN) as a specific example of molecular crystal, we describe the development of a simple coarse-graining procedure by grouping several atoms or whole functional groups into single charge-neutral beads. As compared to fully atomistic calculations the coarse-grained model speeds up simulations by more than two orders of magnitude. Yet, by adjusting only two parameters in the coarse-grained interaction, the model accurately predicts the lattice constants, sublimation energy, pressure-volume curve up to P=10 GPa, and energetically the most stable facets. Computed surface and desorption energies, bulk modulus, and equilibrium morphology are reported as well.

Description:
Starting from an accurate inter-atomic potential we develop a simple scheme of generating an ''on-lattice'' molecular potential of short range, which is then incorporated into a lattice Monte Carlo code for simulating size and shape evolution of nanocrystallites. As a specific example, we test such a procedure on the morphological evolution of a molecular crystal of interest to us, e.g., Pentaerythritol Tetranitrate, or PETN, and obtain realistic facetted structures in excellent agreement with experimental morphologies. We investigate several interesting effects including, the evolution of the initial shape of a ''seed'' to an equilibrium configuration, and the variation of growth morphology as a function of the rate of particle addition relative to diffusion.

Description:
We present a thorough characterization of a capacitor driven arc source that can deliver up to 200 mJ of energy to the arc and high explosive in a well-controlled, repeatable manner on the hundreds of nanoseconds time-scale. Our ultimate purpose is to create a platform to study high explosive kinetics under extreme conditions of high-temperature. In the current paper, we characterize the behavior of our arc source by electrical discharge over a thin PETN film. Temperature and density are determined by time-resolved atomic emission spectroscopy on the nano- to microsecond time scale along with fast photographic imaging to capture time-resolved images of the expanding plasma. We also discuss preliminary simulations of arc plasma using a 1-D hydrodynamic model. Comparisons of these simulations with experimental data are presented. Ultimately our goal is to create a platform that will generate conditions of high temperature in order to study high explosive kinetics. We believe that our arc source platform can be further combined with a time-resolved vibrational spectroscopy (e.g. IR or Raman) to study chemical kinetics under extreme conditions. High temperature conditions may access novel reactive pathways that are different from either shock or slower thermal processes that are substantially lower in temperature.

Description:
XTX8003 is an extrudable explosive composed of 80% PETN and 20% Sylgard 182 (polydimethylsiloxane). Knowledge of the aging characteristics of XTX8003 is desired to understand the relationship between chemical and physical changes and performance. This understanding will allow improved assessment of the current state and also projected lifetime of components that contain this material. A literature search revealed few published studies of the aging behavior of XTX8003 or a chemically similar material, LX-13. Two studies showed that detonation velocity had decreased after storage at 70 C for two years. Another study showed a 30% decrease in target penetration by conical shaped charge after 12 weeks of storage at 82 C. Only one study was found which evaluated chemical and physical changes, but no information was available to correlate performance degradation to chemical and physical changes in the material. In summary, the major changes seen in aged XTX8003 are in detonation velocity and particle morphology, but particle morphology does not appear to be the determining factor in the loss of detonation velocity. The study will continue at least 24 months, at which time the data will be evaluated to determine how best to continue with the remaining test samples.

Description:
Emphasis was placed this quarter on the manufacture of extrudable explosives. This included the recrystallization of PETN which was used to manufacture two batches of LX-02-1 and one batch of RX-02-AK. The materials were examined for composition, extrudability and burning via detonation velocity. Also, a Sunburst and Sunray were performed on the first batch of LX-02 made. Results were all satisfactory except for detonation velocity; some of the channels were yielding somewhat erratic results which could be due either to the test or incomplete mixing. The recrystallization of PETN progressed satisfactorily and the final crystals as viewed under the microscope had the expected appearance.

Description:
Several samples of HMX to be used in LX-04-1 were particle sized and reported in this report. Most of the lots sized were very similar, with the major differences in the lots being at 2{micro}. Several counts in ``Rainbow`` Lot 26B of LX-04-1, made to obtain a color and weight distribution in several samples, and also a color count made in each sieve on a granulation analysis, show each color to be equally distributed; i.e., {approx} one-third of each color, green, yellow and white LX-04-1 granules, was present in the sample. Photographs and particle size curves of recrystallized PETN used in LX-02-1 are presented. These data were obtained by examining the original PETN used in a lot of LX-02-1, then performing several milling operations and recovering the PETN from the binder for another examination. The majority of the PETN appears to be crushed or broken in the first six passes on the three-roll mill with smaller changes taking place in the two-roll mill. The final {Pi} shows most of the PETN to be concentrated in the 4 to 8{micro} region. Photographs of two production lots of LX-02-1 subjected to a milling operation are also included. A description of the procedure used to recover the PETN from the LX-02-1 binder is included. Several solvents for the LX-02-1 binder and for different H.E.`s are listed. These were examined in an effort to find a new elutant to use with LX-04-1. The effects of different milling times on the binder have been examined by checking the solubilities in several of the solvents.

Description:
Micronized PETN was subjected to temperatures above 212{degrees}F for the time periods of 2 to 8 hours to determine if the previous 300-hour cycle could be shortened. It appears that PETN is effectively stabilized after 8 hours at 240{degrees}F. Other PETN samples were treated with wetting agents and also subjected to 240{degrees}F for 8 hours. Seven of the twelve treated samples showed as substantial increase in stabilized surface area with the highest being 16,850 cm{sup 2}/g S{sub 0}{sup P} after being washed with Stein Hall`s Jaguar J2S1. Untreated surface area was 5,000 cm{sup 2}/g S{sub 0}{sup P}.

Description:
Two coupon test samples containing LX-09/Sylgard/Mulberry and LX-10/Sylgard/Mulberry were disassembled for evaluation. Thermal analysis data for the explosives and the analysis of the atmosphere are reported. Identification of several components in the atmosphere was made. The problems associated with the analysis of LX-09 for FEFO by gas chromatography are discussed and the data from the analysis of two specially prepared samples of LX-09 are reported. The data for a series of standard and modified Henkin time-to-explosion for PETN are reported. The modified time-to-explosion runs are first cooled for a fixed time, preheated for 40 to 80 seconds, recooled for a fixed time and then reheated until the sample explodes. A 0.42 cc liquid sample was trapped during the pump out of the W-68 AAU and a preliminary analysis of the sample is reported. The analysis of the atmosphere in the first samples from the PASS A LX-09 evaluation program is reported.

Description:
Two 250-pound batches of LX-09 were made for BAECP for special studies. Twenty Micronizer runs were made to ascertain the effects of various fluids and wetting gents upon the stability of high surface area PETN and to establish the limits within which repeatability can be expected. One sample, after being treated with the wetting agent dodecyl sodium sulfate, stabilized at 7,400 cm{sup 2}/gm after the 300-hour bake at 100 C. A study was begun to determine the effects of deaeration upon the rheological and firing properties of Extex. Rheological data indicate that deaeration has little effect on extrudability. Firing data are currently being obtained.

Description:
Ranchero is an explosively driven magnetic flux-compression generator that has been developed, over the last four years, as a versatile power source for high energy density physics experiments. It is coaxial, and comprises a 15 cm-diameter armature and a 30-cm stator, each aluminum. The length may be varied to suit the demands of each experiment; thus far, lengths of 0.43 m and 1.4 m have been used. The stator is filled and driven by a high performance cast explosive, and the ultimate performance of the device is limited by the smoothness of the armature expansion. The armature explosive is initiated on axis by PETN hemispheres, spaced at intervals of about 18 mm and 24.5 mm; each is simultaneously detonated by a slapper detonator system. Calculations of armature expansion predicted ripples less than 0.2 mm, and this was confirmed in early experiments. Yet, ripples approaching tens of millimeters were observed in some more recent experiments. The authors discuss the possible origins of the se large ripples, and the methods the authors have used to correct them.

Description:
In the manufacture of Extex (XTX 8003, 80% PETN, 20% Sylgard silicone rubber), the formulation is mixed for about five hours. Freon MF is added in the proportions of fur pounds Extex to one quart Freon, to enhance the mixing at lower power than would otherwise be the case. After mixing, the formulation is milled on a three-roll rubber mill for a total of 25 passes. The study of the effects of roll milling on Extex was started; the visual results are indicative that a considerable reduction in crystal size occurs during the formulation process.

Description:
A factorial spark gap detonator study is presented, with the results. UK PETN, (MF 81/10, 6,200 cm{sup 2}/g) at 1.12 g/cm{sup 3} had a higher voltage breakdown and a higher power deposition than others in the test. A somewhat unusual firing system employed for these tests is described. The purpose of the experiment was for determining the effect of specific surface areas (or particle sizes), density, and energy input (including rate of energy input) upon various dependent variables.

Description:
A freeze drying process has been developed which alleviates the caking of high surface area HE powders upon drying and yields a light fluffy textured powder. Three batches of high surface area PETN treated with a surface active agent and two batches of high surface area (Micronizer) RDX have been freeze dried. The RDX powder had a low bulk density of about 0.25 g/cc. Batch sizes ranging from 2 to 10 pounds or more can be easily processed. Samples of the RDX, along with Micronized PETN (surface agent treated and heat stabilized, and untreated), Extex PETN made by a semi-continuous process, and appropriate control samples were each made into 80/20 Sylgard compositions and hand-loaded into ``Sunburst`` assemblies. Some of these assemblies were subjected to 100 C for 30 hours and 300 hours. All of the samples loaded with Micronized PETN and Extex PETN fired satisfactorily, burning to 6-mil thickness of the tapered rays. The RDX fired well also, burning to {approximately} 20-mil thickness of the rays. All the high surface area materials were, of course, very difficult to process at the 20% loading of Sylgard. Several of these samples were also subjected to a detonation velocity test in varying diameter channels. The Micronized PETN behavior was similar to Extex-type PETN.

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